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All Cellate panels are constructed from FRC using Enlarged Ends steel fibers.

The steel fibres are premixed with the concrete in different ratios to suit the engineering requirements of the proposed application. Steel fibres can be carbon steel or stainless steel or be replaced with carbon fibre. The fibres look like pins with flattened heads at both ends as shown in this diagram. The average mix ratio is 70 Kg of fibres per cubic metre of concrete. This will vary with the type of fibres used and the application for which the panel is being constructed. The fibres form a multi dimensional matrix within the concrete during the mixing process. Once cured the fibres are held in place and give an extremely strong core matrix to the concrete which negates the requirement for standard reinforcing methods.

Panel comparison. This comparison looks at a 6 metre by 2 metre by 200 mm flooring panels having equivalent characteristics.

Item	Solid concrete panel	Cellate panel
Concrete	50mPa	50mPa
Cement content		600Kg/m³
Reinforcement	12mm bar at 90mm centres longitudinally and 12mm bar at 300mm centres transversely plus 6mm welded steel mesh at 200mm centres.	70 Kg/m³ Randomly mixed steel fibres.
Weight	0.42 tonnes per metre²	0.16 tonnes per metre²

Load bearing. Load bearing panels have been produced with an overall length of 15 metres. The panels were used to span a gap of 12 metres with a 3 metre cantilever. Panel thickness was only 230mm with a panel weight of 40% of a conventional pre-cast panel.

Versatility. Panels can have beams cast in or openings for various purposes including doors and windows. Curved or complex shaped panels can be produced. The characteristics of a sandwich construction with pre-stressing gives the designer the ability to alter the thickness of walls or floors to meet other design requirements. Changes to skin thickness, core thickness and density, pre-stressing, ribs and edges and the incorporation of architectural, structural and service requirements can be carried out without significant changes to production costs.

Weight. The average density of a Cellate panel is less than 1, therefore the panel will float in water. Additional buoyancy can be designed in for use in floating structures. Compared to conventional panels the Cellate panel is 60% lighter. This leads to the following advantages:

       - Reduction in the dead load of floors and wall panels.
       - Reduces the cost of constructing the supporting structure.
       - Reduction in foundation costs and materials.
       - Reduced handling costs.

Finishing. The out of form finish is good enough to take the paint or finishing system directly without further preparation. Panels can be cast that have the finished inner and outer surfaces in place such as marbleised or stone effect finishes. Floor panels can be cast ready to be polished to a marble finish. This leads to cost and weight reductions in finishing buildings as no additional floor covering or wall cladding is required.

Fixings. A range of cast in fixings are available for the Cellate system that are chosen to contend with the design conditions including wind loadings, seismic conditions and speed of construction. Connections can be stitched, bolted, welded or pre-tensioned.

Standards used in the construction of Cellate panels are:
Portland cement: BS12-1978
Pre-stressing strand BS5896-1980
Aggregate BS812 1:2:3/BS882
Admixtures BS 5075 1:2:3
Inner core BS 3241
Fibre steel EE 184, 186, 252, 455, 800mPa

A typical wall panel constructed to these standards could be only 75 mm thick and would consist of the following materials and properties:

Panel structure:
          Concrete              50mPa
          Cement content     600Kg/m3
          Fibre steel             70Kg/m3

Pre-stressing tendon Belgium indent 12mm2 in quad configuration
Minimum bursting load 168 kN
Minimum tensile strength 280mPa

Inner core:
Type A Portland cement                              400Kg/m3
1 metre3 polystyrene bead/dried rice husk   = 480Kg/m3

Advantages. The Cellate panels have a number of significant advantages over conventionally produced pre-cast panels due to the use of 600-800 Kg/m3 of type A Portland cement with a 0.45 water ratio. This mix meets all the requirements of ASTM, British Standards (BS) and the American Standards Association (ASA). The result is:

      Cellate has twice the abrasion resistance..
      Over twice the punching sheer resistance.
      Higher fatigue resistance permitting more repetitions of loading without distress.
      Four times the impact resistance.
      Young’s modulus and Poisson’s ratio are unaffected by the fibre steel content.
      Exposure to seawater for 20 years has shown only negligible corrosion.

Thermal properties. Concrete has limited thermal resistance on its own. The construction of the Cellate panel core ensures that the Cellate panels meet the highest standards for thermal resistance. Where increased thermal/insulation properties are required the core thickness can be increased. Cellate panels were tested in Canada where thermal test properties are stringent due the cold climatic conditions. A 200mm Cellate panel was tested and exceeded the test requirements by a significant margin.

Dimensional accuracy. The Cellate panels are a factory produced panel with stringent quality control standards. Panels are produced in steel moulds to ensure consistent quality throughout the production run. All panels leaving the plant are checked to ensure they match the dimensions stipulated for the panel.

Dimensional stability. Due the nature of the design and the high quality of the materials used throughout, all Cellate products are dimensional stable in use.

Speed of assembly. Assembly and site time is minimised as all the Cellate system delivers an accurately produced system to site with all fixings incorporated. Larger lighter panels are used meaning less handling operations are required to construct a given area. Panels are lighter and require less manpower and lower capacity lifting equipment. With the fixings cast in, the components are very simple and quick to assemble. The building can be erected quickly which minimises the impact of weather on the construction and enables the internal fit out to proceed at an earlier stage.

Fire resistance. Fire resistance tests on 100mm panels showed resistance for up to 4 hours at 1150 degrees Celsius compared to 1 hour for conventional concrete. Cellate panels at 200mm thickness are commonly used in chemical storage facilities to provide an 8 hour fire rating.

Summary of characteristics:
Minimum compressive strength             50mPa at 28 days.
Minimum flexural strength                    7mPa at 28 days.
Los Angeles abrasion min value             75%.
Shrinkage reduction                           10%.
Punching sheer resistance                   50%.
Flexural fatigue                                  75% modulus of rupture.
Elastic properties in flexure                  72.2 x 10.3mPa.
Permeability 100 hour test                   3.3 x 10-12mm/m2/sec.
Thermal expansion at 27Co                  8.2 x 10-6per Co
Modulus of elasticity in compression      27.3 x 10-3mPa

List of reference links:
Industrial : W. R. Grace, Rocla Technology (Australia), E. I. Du Pont, Conoco Inc., Eternit Corp. (Switzerland), Kuraray Corp. (Japan), and Redco Corp. (Belgium), Fundia (Norway).

Bache, H. H. in Fracture Mechanics of Concrete Structures: From Theory to Applications; Elfgren, L., Ed.; Chapman & Hall: London/New York, 1989; pp 382-398.

Craig, R. Flexural Behavior and Design of Rein- forced Steel Fiber Concrete Members; ACI-SP105, 1987; pp 517-564.

Horii, H.; Nanakorn, P. in Proceedings of the ACI International Workshop on Seismic Effect in Concrete Structures; Sendai, Japan, 1993; pp 347-358.

Kanda, T.; Watanabe, S.; Li, V. C. Fracture Mechanics of Concrete Structures, Proceedings FRAMCOS-3, AEDIFICATIO Publishers: Freiburg, Germany, Oct. 1998, pp 1477-1490, to appear.

Li, V. C.ASCEJ Mater Civil Eng 1992,4(1),41-57. 30. Li, V. C. in Steel Fiber Reinforced Concrete: Present and the Future; Banthia, N.; Bentur, A.; Mufti, A., Eds.; Canadian Society for Civil Engineering: Montreal, 1998; pp 64-97.

Mishra, D. Ph.D. Thesis, University of Michigan, Ann Arbour, MI, 1995.

Mufti, A. A.; Jaeger, L. G.; Bakht, B.; Wegner, L. D. Can J Civil Eng 1993, 20, 398-406.

Naaman, A. Fiber Reinforcement for Concrete; Concrete International, March, 1985; pp 21-25.

Naaman, A. E. in Proceedings of the International Workshop on High Performance Steel Fiber

Reinforced Composites; Reinhardt, H. W.; Naaman, A., Eds.; Mainz, 1991; pp 18-38.

Packard, R. G.; Ray, G. K. FRC International Symposium, ACI SP-81 1984, 325-348
.
Richard, P.; Cheyrezy, M. H. ACI Convention, San Francisco, CA, 1994.